In the case where facility elements inside a building are monitored with the use of a monitoring device, it is necessary that the self-localization of the monitoring device inside the building should be estimated.
Because a GPS (global positioning system) cannot be used inside a building, any of self-localization estimation methods is needed instead of the GPS. One of such self-localization estimation methods that can be used is a self-localization estimation method for a self-running robot disclosed in Nonpatent Literature 1.
According to this method, the self-localization of a monitoring device can be estimated by measuring the shapes and positions of peripheral objects with the use of a laser range finder disclosed in Patent Literature 1 and by collating (matching) the measured result with a prepared map. Such a self-localization estimation method is called a scan matching.